In some fluid ejection devices, a flow path including a fluid pumping chamber and a nozzle can be formed in a substrate. Fluid droplets can be ejected from the nozzle onto a medium, such as in a printing operation. The fluid pumping chamber can be actuated by a transducer, such as a thermal or piezoelectric actuator, and when actuated, the fluid pumping chamber can cause ejection of a fluid droplet through the nozzle. The medium can be moved relative to the fluid ejection device, e.g., in a media scan direction. The ejection of the fluid droplet can be timed with the movement of the medium to place a fluid droplet at a desired location on the medium. A fluid ejection device typically includes multiple nozzles, such as a line or an array of nozzles with a corresponding array of fluid paths and associated actuators, and droplet ejection from each nozzle can be independently controlled by one or more controllers. It is usually desirable to eject fluid droplets of uniform sizes and speed, and in the same direction, to provide uniform deposition of fluid droplets on a medium.